Rotary flow forming apparatus

ABSTRACT

A rotary flow forming apparatus for producing light alloy rims contains a main spindle with a clamping apparatus for a rim blank. An outer pressure roller is provided and is deliverable radially from the outside in and is movable parallel to the spindle axis, for producing an outer contour of the light alloy rim. The apparatus does not require massive internal dies and thereby significantly reduces the production costs and significantly improves the efficiency of rim production, which is achieved by the fact that the rotary flow forming apparatus has an inner pressure roller for generating an inner contour of the light alloy rim, which is arranged in the region of the inner side of the rim blank opposite the outer pressure roller and is mounted so as to be movable parallel to the spindle axis, rotatable, and deliverable radially from the inside outward to the rim blank.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority, under 35 U.S.C. § 119, of German application DE 10 2017 123 997.9, filed Oct. 16, 2017; the prior application is herewith incorporated by reference in its entirety.

BACKGROUND OF THE INVENTION Field of the Invention

The invention relates to an apparatus for manufacturing light alloy rims for a motor vehicle from a rotary flow forming apparatus for flow-turning. The rotary flow forming apparatus contains a main spindle with a clamping apparatus for a cup-shaped rim blank and at least one outer pressure roller that may be delivered radially thereto from the outside in and may be moved parallel to the spindle axis, for generating an outer contour of the light alloy rim.

Known in the art is a rotary forging apparatus, from published European patent application EP 0 652 061 A1 (corresponding to U.S. Pat. No. 5,553,088), having an inner ram in addition to an outer pressure roller, but this tool does not directly work on a rim blank, instead serving to hold in place an internally hollow die.

A drawback of this previously known rotary forging apparatus is that the die, as also in the case of conventional rotary forging tools, must have a preformed inner shape of a wheel disc of a light alloy rim; thus, a separate die must be kept ready for each variant of a light alloy rim. This is very costly in terms of money and effort, and requires considerable storage capacities for the different dies.

Furthermore, the overall contour of the die must be such that the manufactured light alloy rim may be released from the die, which significantly limits the freedom of design for a rim manufacturer.

Also known in the prior art is a flow forming machine for manufacturing rotationally symmetrical hollow bodies, DE 1 900 354 A, by means of which hollow bodies deformed in a tapered or conical shape may be produced from circular sheet metal disks of small thickness that are perpendicular to a spindle axis of the apparatus. However, this method of metal forming is not suitable for manufacturing light alloy rims having a hollow cylinder-like cup shape.

SUMMARY OF THE INVENTION

The objective of the invention is to provide an apparatus for manufacturing light alloy rims for a motor vehicle that does not require massive internal dies and thereby significantly reduces production costs and significantly improves the efficiency of rim production.

The objective is achieved according to the invention, in conjunction with the features of the preamble, in that the rotary flow forming apparatus has at least two inner pressure rollers for generating a hollow cylindrically-shaped inner contour of the light alloy rim, which is arranged in the region of the inner sides of the rim blank opposite the at least two outer pressure rollers and are mounted so as to be movable parallel to the spindle axis, rotatable, and radially deliverable from the inside outward to the rim blank.

The inventive rotary flow forming apparatus makes it possible to produce a light alloy rim entirely without the presence of a predetermined massive die, because the inner shape of the wheel disc may be shaped by the inner pressure rollers, which move from the outside inwards against the inner wall of a rim blank and may be movable in the direction parallel to the spindle axis, so that inner shapes of wheel discs may be made, which could not have been formed with a conventional die.

This flow-forming, in contrast to the metal pressing known in the prior art, causes the light alloy to flow completely, so that a high thin-walled rim profile may be generated from a short thick-walled cup of a rim blank.

Another significant advantage of the inventive rotary flow forming apparatus is that the need for switching dies is completely eliminated, because there are no such dies any more, and accordingly they do not have to be mounted and prepared in advance; in this way, a very significant cost factor in the production of light alloy rims is completely eliminated.

Further advantageous configurations of the subject matter of the invention will become apparent with, and in combinations of, the subsequent dependent claims.

Corresponding to a preferred embodiment of the invention, the inner pressure roller is equipped with a rotational axis that is set angularly against the spindle axis, which in a further variant may be variably mounted inside its angle of attack over the length of the travel path parallel to the spindle axis, so that, for example, even inner areas of the wheel disk may be involved; in this way, a rim blank for a light alloy rim may be optimally deformed.

A particularly preferred embodiment of the manufacturing apparatus according to the invention is equipped with inner pressure rollers, which are arranged on the opposite side of the main spindle of the rotary flow forming apparatus on a common feed unit on which they are mounted to be able to move radially transversely to the spindle axis independently of each other, the feed unit being so designed as to be able to move axially in a longitudinal direction together with the pressure rollers. Such an arrangement is extremely stable and durable, because the opposing radial deformation forces both bear on the feed unit and cancel each other out.

According to another advantageous embodiment of the invention, a pair consisting of an outer pressure roller and an inner pressure roller that acts oppositely from within is arranged on a shared bracket part, and this bracket part is configured to be movable parallel to the spindle axis, so that the inward and outward forces of the inner and outer pressure rollers cancel out and the system remains free of externally-acting forces.

Also advantageous is a configuration of the subject matter of the invention wherein a plurality of outer pressure rollers and one or more inner pressure rollers have, in particular in the presence of two or three outer pressure rollers, a number of inner pressure rollers corresponding to the number of outer pressure rollers. The inner and outer pressure rollers being arranged respectively opposite each other, so as to achieve a substantial or even complete absence of outward forces.

In a particularly preferred configuration of the invention, two pairs of outer and inner pressure rollers are arranged offset from each other in the range of 180° about the spindle axis, so that the external forces that are laterally applied will cancel each other or at least partially compensate for one another. A third pair of outer and inner pressure rollers may here additionally be arranged, offset in the range of 90° about the spindle axis between the first two pairs, in order to further increase the required deformation performance.

Another advantageous version of the subject matter of the invention, in contrast, has three pairs of outer and inner pressure rollers, which are arranged offset in the range of 120° about the spindle axis with respect to each other, so as to cancel each other or largely compensate for the laterally applied forces.

The rotary flow forming apparatus preferably has a main spindle with a clamping apparatus on which the later outer end face of a wheel disc of a light alloy rim is held clamped, preferably having an inner clamping apparatus by which a rim blank from the later inner end face of the wheel disc is pressed toward the main spindle through openings in the rim blank. It is also advantageously possible to use a separate holding stamp with an axial holding force in the direction of the clamping apparatus.

Quite especially advantageous is an embodiment of the invention, in which heating shoes, which are equipped with induction heaters, are arranged on the main spindle and/or on the one or more pressure rollers and/or inside and/or outside in a contactless arrangement to the cylindrical surface of the wheel disc of the rim blank or the light alloy rim, so that the light alloy to be deformed may be kept at a temperature required for this purpose, a task to which this contactless heating system is exceptionally suited.

Other features which are considered as characteristic for the invention are set forth in the appended claims.

Although the invention is illustrated and described herein as embodied in a rotary flow forming apparatus, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.

The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagrammatic, illustration of a clamping apparatus of a rotary flow forming apparatus with a shared feed unit for the inner pressure rollers and with a clamped rim blank or clamped light alloy rim; and

FIG. 2 is an illustration of the clamping apparatus of the rotary flow forming apparatus with a shared bracket part for an outer and an inner pressure roller and with a clamped rim blank or clamped light alloy rim.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to the figures of the drawing in detail and first, particularly to FIG. 1 thereof, there is shown a rotary flow forming apparatus which has a main spindle 1 with a clamping apparatus 15, on which a cup-shaped rim blank 2 is held clamped which is formed there into a light alloy rim 11; for this purpose, the main spindle 1 of the rotary flow forming apparatus is rotated about the spindle axis 3 and outer pressure rollers 4, 5 are pressed from the outside and the inner pressure rollers 6, 7 are pressed from the inside against the rim blank 2 and are moved in the longitudinal direction of the spindle axis 3 so that the light alloy rim 11 is generated having desired outer and substantially hollow cylindrically-shaped inner contours of the wheel disc.

Rotational axes 12,′ 13′ of the outer pressure rollers 4, 5 are generally oriented parallel to the spindle axis 3; in contrast, axes of rotation 12, 13 of the inner pressure rollers 5, 6 are set at an angle to the spindle axis 3, and this angle may be made variable, so that, for example, even in the region of the wheel disc, an inner partial deformation may take place, while the inner pressure rollers 6, 7 in the end portion of the light alloy rim 11 opposite the wheel disc may take a position that is parallel to the spindle axis 3 or is pivoted further.

The inner pressure rollers 4, 5 of a first version of the manufacturing apparatus, as shown in FIG. 1, are arranged on a shared feed unit 19, where they are mounted independently of each other and are capable of moving radially transversely to the spindle axis 3, the feed unit 19 being designed to be capable of moving axially longitudinally in the direction of the spindle axis 3.

In a second version of the manufacturing apparatus, as shown in FIG. 2, a pair of an outer pressure roller 4, 5 and an inner pressure roller 6, 7 operating in the opposite direction are arranged on a shared bracket part 14 which is designed to be movable parallel to the spindle axis 3.

The manufacturing apparatus additionally has the inner clamping apparatus 15 by means of which the rim blank 2 is pressed toward the main spindle 1 by its later inner end face 10 through openings in the rim blank 2.

In addition, the main spindle 1 and/or the pressure rollers 4, 5, 6, 7, inside and/or outside, is or are equipped with heat shoes 16, 17, 18 of an induction heater in a contactless arrangement with respect to the cylindrically shaped surface of the rim blank 2 or the light alloy rim 11. 

1. A manufacturing apparatus for manufacturing light alloy rims for use on a motor vehicle, comprising: a rotary flow forming apparatus containing: a main spindle with a spindle axis and a clamping apparatus for receiving a cup-shaped rim blank; at least one outer pressure roller being deliverable radially from an outside in and is movable parallel to the spindle axis, for producing an outer contour of a light alloy rim from the cup-shaped rim bank; and at least two inner pressure rollers for generating a hollow-cylindrically-shaped inner contour of the light alloy rim from the cup-shaped rim bank, disposed in a region of an inner side of the cup-shaped rim blank opposite said at least two outer pressure rollers, and are mounted so as to be movable parallel to the spindle axis, rotatable, and deliverable radially from inside outward to the cup-shaped rim blank.
 2. The manufacturing apparatus according to claim 1, wherein said inner pressure rollers each respectively have rotational axes that are inclined against the spindle axis.
 3. The manufacturing apparatus according to claim 2, wherein the rotational axes of said inner pressure rollers are variably mounted inside an angle of attack over a length of a travel path parallel to the spindle axis.
 4. The manufacturing apparatus according to claim 1, further comprising a shared feed unit, said inner pressure rollers are disposed on said shared feed unit, said inner pressure rollers are mounted so that they may move radially transversely to the spindle axis independently of one another, and in that said shared feed unit is configured so that it may move axially longitudinally in a direction of the spindle axis together with said outer pressure rollers.
 5. The manufacturing apparatus according to claim 1, further comprising a shared bracket part, said outer pressure roller and said inner pressure roller define a roller pair operating in opposite directions and are disposed on said shared bracket part which is configured to be movable parallel to the spindle axis.
 6. The manufacturing apparatus according to claim 1, wherein said at least one outer pressure roller is one of a plurality of outer pressure rollers.
 7. The manufacturing apparatus according to claim 1, wherein: said at least one outer pressure roller is one of a plurality of outer pressure rollers; said inner pressure rollers corresponding to a number of said outer pressure rollers and are respectively disposed opposite one another.
 8. The manufacturing apparatus according to claim 6, wherein two pairs of said outer pressure rollers and said inner pressure rollers are disposed offset from each other in a range of 180° about the spindle axis.
 9. The manufacturing apparatus according to claim 8, wherein a third pair of said outer pressure roller and said inner pressure roller is disposed between said first two pairs, offset about the spindle axis in a range of 90°.
 10. The manufacturing apparatus according to claim 6, wherein three pairs of said outer pressure rollers and said inner pressure rollers are disposed offset about the spindle axis in a range of 120° relative to each other.
 11. The manufacturing apparatus according to claim 6, wherein an outer end face of the light alloy rim is clamped to said clamping apparatus.
 12. The manufacturing apparatus according to claim 10, further comprising an inner clamping apparatus by means of which the rim blank, from its later inner end face toward said main spindle, is pressed thereto through openings in the cup-shaped rim blank.
 13. The manufacturing apparatus according to claim 1, wherein said main spindle and/or said inner and outer pressure rollers, inside and/or outside, is/are equipped with heat shoes of an induction heater in a contactless arrangement about a cylindrically-shaped surface of the cup-shaped rim blank or the light alloy rim. 